IMUs are wildly expensive, and still have quite a lot of drift: https://news.ycombinator.com/item?id=10752294 https://news.ycombinator.com/item?id=10752294 Cer

IMUs are wildly expensive, and still have quite a lot of drift: https://news.ycombinator.com/item?id=10752294 https://news.ycombinator.com/item?id=10752294 Certainly the RQ-170 has an IMU, and I could believe it might use it as the primary means of navigation, but it's almost certainly corrected by GPS, which gives you a means of altering the drone's path by GPS spoofing.